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Gross then appeared to get in the final jab, telling a CNBC interviewer that he and his wife had committed to giving away all their money before they die. He invoked 19th century steel magnate and philanthropist Andrew Carnegie, who maintained that the wealthy were obligated to use their money to improve society.

The contretemps came just as Gross published his November investment outlook in which he excoriated 1% “scrooges” and called for “an equitable rebalancing of personal income taxes, capital gains and carried interest.”

Icahn, who has a net worth of some $15 billion, was an early signatory to the Giving Pledge.

Gross, whose personal worth is estimated at $2 billion, has endowed a foundation with nearly $300 million and raised money for other charities by selling parts of his stamp collection, according to Bloomberg.